getBody method Null safety

Implementation

@override
List<Widget> getBody() => <Widget>[
      _getListTile(
        appLocalizations.contribute_improve_header,
        () => _contribute(),
      ),
      _getListTile(
        appLocalizations.contribute_sw_development,
        () => _develop(),
      ),
      _getListTile(
        appLocalizations.contribute_translate_header,
        () => _translate(),
      ),
      _getListTile(
        appLocalizations.contribute_donate_header,
        () => _donate(),
        icon: const Icon(Icons.open_in_new),
      ),
      _getListTile(
        appLocalizations.contributors,
        () => _contributors(),
      ),
    ];